body {
  height: 100vh;
  /* background: url() no-repeat; */
  background-size: cover;
  display: flex;
  /* justify-content: center;
    align-items: center; */
}

.first {
  color: rgba(255, 166, 0, 0.771)
}

ul {
  padding: 10px;
  width: 10%;
  margin: auto;
  list-style: none;
  /* background: radial-gradient(rgba(0, 191, 255, 0.211),
        rgba(0, 0, 255, 0)); */
  display: flex;
  float: left;
}

.li {
  flex: 1;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  width: 100%;
}

a {
  text-decoration: none;
  color: black;
  display: block;
  width: 100%;
  font-family: serif;
  font-weight: 1000;
  padding: 10px 0;
  text-align: center;
  font-size: 120%;
}

/* 这里font-size用百分比好用多了 */
a:hover {
  color: rgba(255, 166, 0, 0.771);
  transition: all 0.3s;
}


.li::before {
  content: '';
  position: absolute;
  width: 0;
  left: 50%;
  bottom: 0;
  height: 3px;
  background-color: rgba(255, 166, 0, 0.771);
}

.li:hover::before {
  width: 80%;
  left: 10%;
  transition: all 0.5s;
}



ul:hover .a {
  display: block;
  width: 8%;
}

ul:hover .b {
  display: block;
  width: 8%;
}

ul:hover .c {
  display: block;
  width: 8%;
}


.AA {
  margin: 0 40px 0;
  width: 100%;
  height: 70px;
  position: fixed;
  box-shadow: 10px 2px 5px #888888;
  /* background-color: white; */
  display: block;
  z-index: 999;
}

h3 {
  right: 250px;
  position: absolute;
  font-family: serif;
  font-weight: 800;
  top: 0
}


/* 轮播图 */
body {
  font-family: Arial, sans-serif;
}

.carousel {
  position: relative;
  width: 100%;
  max-width: 600px;
  margin: auto;
  overflow: hidden;
  top: 10px;
  height: 500px;
}

.carousel-inner {
  display: flex;
  transition: transform 0.5s ease-in-out;
}

.carousel-item {
  min-width: 100%;
  box-sizing: border-box;
}

.carousel-item img {
  width: 100%;
  display: block;
  height: 500px
}

.carousel-control-prev,
.carousel-control-next {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 30px;
  height: 30px;
  background-color: rgba(0, 0, 0, 0.255);
  border-radius: 10%;
  color: #fff;
  text-align: center;
  line-height: 30px;
  cursor: pointer;
}

.carousel-control-prev {
  left: 10px;
}

.carousel-control-next {
  right: 10px;
}